Integrated tank containers for the bulk storage of liquids

ABSTRACT

An integrated membrane-type tank container for cryogenic liquids, supported within a rigid outer shell, is made up of a multiplicity of panels in the form of shallow boxes of thin, flexible metal sheet material filled with load-bearing insulation, and sealingly connected together by edge extensions of their front and back faces respectively to provide inner and outer impervious membrane walls, which walls are attached to a support framework carried by the rigid outer shell. The edge extensions of adjacent panels are welded together through metal strips folded to provide expansion joints and the shallow boxes are attached to the framework through these strips. The framework is provided with brackets for adjusting the spacing of individual frame members from the outer rigid shell to facilitate even alignment of the shallow boxes.

United States Patent [1 1 Jackson Apr. 2, 1974 [54] INTEGRATED TANKCONTAINERS FOR 3,302,358 2/1967 Jackson 220 9 LG x THE BULK STORAGE 0FLIQUIDS 3,341,049 9/1967 Forman et al. l l4l74 A X 3,547,302 l2/l970Jackson l'l4/74 A X [75] Inventor: Robert G. Jackson, I-Iornchurch,

England FOREIGN PATENTS OR APPLICATIONS l 7163 G B" ..2209LG [73]Assignee: Conch International Methane 93258 9 real mam I Llmned NassauBahamas Primary Examiner-Herbert F. Ross [22] Filed: Mar. 8, 1971Assistant Examiner-Stephen Marcus 1 pp No: 121,976 Attorney, Agent, orFzrmMax L. Llbman o [57] ABSTRACT [30] Foreign Apphcat'ml Priority DataAn integrated membrane-type tank container for cryo- Mar. 19, 1970 GreatBmam 13247/70 genie liquids Supported within a rigid outer She, is

made up of a multiplicity of panels in the form of shal- [52] 220/9 LG,220/10 220/15 low boxes of thin, flexible metal sheet material filled[51] Int. CL, B65d 25/18 with loadbearing insulation, a sicalinglyconnected [58] Fleld Search 220,9 9 together by edge extensions of theirfront and back 114/74 A faces respectively to provide inner and outerimpervious membrane walls, which walls are attached to a [56] Referencescued support framework carried by the rigid outer shell.

UNITED STATES PATENTS The edge extensions of adjacent panels are weldedto- 3,15o,793 9/1964 Messer 220 9 F gather through metal Strips foldedto Provide p 2,744,042 5/1956 Pace 2220/) F sion joints and the shallowboxes are attached to the 2,896,271 7/1959 Kloote et al 220/9 Fframework through these strips. The framework is 7 4 H1 L r x 2 LGprovided with brackets for adjusting the spacing of ingoctfrellui...dividual frame members from the outer rigid shell to g yeta 3,150,7949/1964 Schlumberger et al. 220 9 LG facfl'tate ahgnnlem of the ShallowbDXes' 3,298,345 1/1967 Pratt 220/15 X 3 Claims, 3 Drawing FiguresPATENTEDAPR 21914 3.800.970

' sum 1 0F 3 lnvenlor Robe/7' G Jbc K5011 M74 Attorney Inventor Roberf GJae/@5014 44 4 Attorney PATENTEDAPR 2mm SL800 9 70 SHEEI3UF3 InventorINTEGRATED TANK CONTAINERS FOR THE BULK STORAGE OF LIQUIDS Thisinvention relates to integrated tank containers for the bulk storage ortransport of liquids at temperatures greatly differing from ambienttemperature. The invention is primarily intended for containers for coldliquids such as liquefied gas, e.g., natural gas, and petroleum gas, butit may also be applicable to containers for housing warm liquids.

An integrated tank container comprises essentially a housing ofload-bearing thermal insulation supported within an outer rigid sheeland lined internally with a thin and flexible fluid-tight membrane(hereinafter referred to as a primary membrane) of sheet material, e.g.,in the case of liquefied gas, a metal which is not subject to coldembrittlement, the primary membrane being supported against internalloads due to hydrostatic pressures and inertia forces by the surroundingthermal insulation. The invention is particularly concerned with anintegratedtank container. of the kind including a further or a secondarymembrane similar to the primary membrane which surrounds the housing ofload-bearing thermal insulation.

It is normal practice to assemble such containers from within the spaceto be enclosed by said container and this is usually achieved bycompleting the construction of each layer, i.e., the two membranes andthe load-bearing thermal insulation, in turn starting from the outermostlayer. This practice is very timeconsuming and costly since it requiresa high standard of accuracy inaligning and assembling the componentparts of each layer at site. These component parts may comprise, forexample, sheets or panels for the membranes, and solid insulationpanels, or boxes made of solid insulation material filled with loosegranular insulation material, for the load-bearing thermal insulation.

Also with a container of this kind it is usually necessary I plicityofprefabricated relatively shallow boxes of a suitable thin and flexiblesheet material, which boxes are sealingly connected together aroundtheir side walls, said walls are attached to a support framework carriedby the outer rigid shell, and said housing is provided by fillings ofload-bearing insulation material contained within said boxes.

Where the container is substantially plane-faced, preferably those boxesproviding the plane-faced portions contain fillings of load-bearingthermal insulation, the corner portions of the container being providedby curved boxes which contain fillings of thermal insulation materialwhich is of a loose or resilient nature.

The side walls of the boxes may include edge portions of at least thefaces providing the secondary membrane which extend beyond said sidewalls in which case, a set of connecting members is attached to thesupport framework for sealing together co-operating edge portions ofthese faces, a further set of connecting members is provided for sealingtogether the faces providing the primary membrane, and each spacedefined between the two sets of connecting members and the side walls ofadjacent boxes contains a further filling of said insulation.

Conveniently the further set of connecting members for the primarymembrane may be carried on the inner faces of said further fillings ofinsulation.

Said sealing between the faces may be effected in accordance with amethod described in co-pending U.S. Patent Application by Robert G.Jackson and Edward Armstrong for Methods of Welding Together Sheets toForm Walls, Tanks or the Like in which, for example, use is made of setsof connecting members of generally T-shaped cross-section. Withconnecting members of such cross-section the further fillings of thermalinsulation are preferably formed with slots which embrace the stems ofthe set of connecting members for the secondary membrane to locate saidfurther fillings in position.

The prefabricated boxes may be evacuated and/or purged with an inert gasduring their construction.

Thesupport framework may be attached to the outer rigid shell viabrackets which provide for adjustment of the spacing of the framemembers of said framework from the outer rigid shell. Such anarrangement facilitates the even alignment of the support faces of theframe members should any undulations be present in the outer rigidshell.

It will be appreciated that because the boxes with their fillings areprefabricated and provide the two membranes and the housing of thermalinsulation, the amount of site alignment and assembly is reducedconsiderably, a high standard of accuracy being required only for theinitial alignment of the boxes on the support framework.

In order that the invention may be readily understood one. embodimentthereof will now be described by way of example with reference to theaccompanying drawings in which:

FIG. 1 is a section through part of the container;

FIG. 2 is an enlarged sectional view of a corner of the container; and

FIG. 3 is an enlarged'fragmentary perspective view of a detail of thecontainer.

Referring to FIGS. 1 and 2, the container is of planefaced form andcomprises a primary membrane 1 which lines a housing 2 of load-bearingthermal insulation, a secondary membrane 3 extending around the housing2 and attached to an outer rigid shell 4 via hardwood frame members 5which are arranged to provide a rectangular lattice framework. In thisembodiment the housing 2 except at its corners comprises balsa woodpanels 6 and the primary and secondary members 1, 3 are of aniron-nickel alloy having a very low co-efficient of expansion; asuitable alloy is that sold under the Registered Trademark INVAR.

In accordance with the invention the primary and secondary membranes 1,3 of the plane-faced portions of the container are provided by the twosets of faces 7, 8 respectively (see FIG. 2) of a multiplicity ofshallow boxes 9 which are welded together, the balsa wood panels 6 ofthe housing 2 providing fillings for these boxes. The faces 8 of theboxes 9 have peripheral edge portions which extend beyond the sides 10of their boxes so that each box may be aligned over an opening of thelattice framework with its extended edge portions 1 1 overlapping theframe members 5. The support faces'of the frame members have attachedthereto connecting members 12 which are formed by folding strips ofINVAR (Registered Trademark) and are of generally T-shapedcross-sectior'1. The arms 13 of each connecting member are extended ashort distance around the sides of their frame member for attachment tothe latter. The stem 14 of each connecting member is enlarged at itsfree end as shown at 15 to provide a rail on which a welding machine(not shown) may be mounted for welding the edge portions 11 of itsrespectween the side walls of adjacent boxes is filled with a furtherpanel 16 of balsa wood, this panel being provided with a slot 17 forclipping onto the rail of said connecting member. The inner face of eachfurther panel 16 has attached thereto a further connecting member 19,similar to the connecting member 12, the arms 20 of which, with thepanel 16 in its located position, extend across the faces 7 of theirrespective pair of boxes 9. The arms 20 are then welded to theirrespective faces 7 by the method referred to hereinbefore with respectto the connecting member 12. g

The rectangular lattice framework provides openings of regular size overmost of the area of the plane-faced portions of the container and hencethe boxes 9 for those openings are of a standard size. The dimensions ofthe container may be chosen such that said planefaced portions areassembled complete from standard boses 9. However, it will beappreciated that where the dimensions are not so chosen further boxes ofsuitable dimensions, for example such as shown at 9a in FIG. 1, may beused in conjunction with the standard size boxes.

Each frame member 5 is supported at spaced positions in metal cradles21, preferably of 9% nickel-steel,

which in turn are attached to hardwood blocks 22. Further metal cradles23, also of 9% mickel-steel, are attached to the outer rigid shell 4 andembrace each hardwood block 22. The walls of each cradle 23 are providedwith slots 24 (see FIG. 3) through which bolts 22a (FIG. 2) may pass andthrough apertures (not shown) extending through the respective hardwoodblock 22. Thus, the spacing between the support face' of each framemember 5 and the outer rigid shell 4 may be adjusted within the limitsof the slots 24 of the cradles 23 wherebythe support faces of all of theframe members 5 may be aligned to provide an even surface on which theboxes 9 are located. Each cradle 21, 23 is provided with a 'pair of thinwebs 25, 26 respectively of 9% nickel-steel arranged to be weldedtogether once the spacing of the frame members 5 from the outer rigidshell 4 is set.

- Where the frame members 5 of the framework intersect, the supportarrangement therefor includes a metal cradle 27-which is of cruciformshape (see FIG. 3).

I Otherwise the support arrangement is similar to that described above.

The corners of the container are provided by further prefabricated boxes28 similar to the boxes 9. However, the boxes 28 are curved, i.e., inthe case ofa dihedral comer they are radiussed as shown in FIG. 2 and inthe case of a trihedral corner they are part spherical. Also these boxescontain a filling of loose or resilient non-load-bearing thermalinsulation, e.g., a mineral wool, thus permitting the boxes to flex anddeform depending upon the stresses and loads to which they are subjectedin use.

Preferably, the connection between each frame member 5 and itsconnecting member 12 is strengthened, particularly adjacent the cornersof the container by welding the edges of the horizontal 13 of theconnecting member to the metal cradles 21.

It will be appreciated that the arrangement described above for weldingthe boxes 9, 28 together is such, with the balsa wood panels 6 and 16being constrained by the side walls 10 of the boxes 9, that said panelsact as keys to maintain the faces 7 of the plane-faced portions of thecontainer substantially in their relative positions.

However, particularly at the corners of the container, should excessivestresses or loads be induced in use, the resilience of the walls IOmaypermit some movement of the boxes 9 to take place thus permitting thecorner boxes 28 to deform. Such movement of the boxes 9 may be increasedby providing inserts within the boxes 9 of, for example, compressed woolbetween the edges of the fillings 6 and their respective sides 10 ofsaid boxes. Furthermore, a copper strip may be provided within the boxes9, 28 adjacent to those parts of the faces 7 to which the connectingmembers 19 are to be welded, said copper strips thus providing a heatsink during the welding process.

If required, secondary frame members 29 (see FIG. 1) may be providedlocated between the frame members 5 to provide additional support forthe boxes 9 and the support arrangement for the frame members 29 may bethe same as that described for the frame members 5. The frame members 29would not carry connecting members 12. With such an arrangement thespace 30 between the boxes 9, 28 and the outer rigid shell 4 may befilled with a loose thermal insulation material such as mineral wool, orgranular material such as that sold under the Registered Trademark PER-LITE. Alternatively, the space 30 may be provided with a load-bearingthermal insulation system, which may comprise, for example, a two-partinsulation system similar to that described in my co-pending US. Pat.application Ser. No. 801,495, particularly with reference to FIG. 4.Thus, the two-part insulation system may comprise a framework of solidinsulation panels, e.g., balsa wood, defining areas containing rigidfoamed plastics material, e.g., polyurethane. With this alternativearrangement the additional frame members 29 would not be required sincethe boxes 9 would be supported against the inner faces of the two-partinsulation system.

The container construction as hereinbefore described includes thefollowing advantages when compared with a construction in which themembranes and load-bearing thermal insulation are built up in layers:

pletely, the boxes 9 and 28' may each be of uniform size.

iii. Due to their prefabrication away from the site, for safety reasons,the boxes 9 and 28 may be purged of air with an inert gas such asnitrogen or carbon dioxide. Alternatively the air may be evacuatedinwhich case the insulation properties of the boxes may be improved.Preferably these operations would be carried out through the side walls10 of the boxes.

iv. The primary membrane 1 is rigidly tied to the frame members 5 viathe sides 10 of the boxes 9, 28. Although the sides 10 provide heatpaths through the housing 2 of thermal insulation, the effect of theseheat paths is minimized by the thinness of the membrane material.

v. Because the fillings of thermal insulation are contained completelywithin the boxes 9, 28, should the primary membrane 1 be punctured inuse, any damage occurring is localized.

vi. Because the secondary membrane 3 is tied to the primary membrane 1via the side walls 10 of the boxes 9, 28, a further housing ofload-bearing thermal insulation for supporting the second membrane isnot essential.

vii. Because each plane-faced portion of the container provided by theboxes 9 is independent of each of its adjacent wall portions due to saidboxes being mounted directly on the framemembers 5, the corner boxes 28may be of any desirable shape to fill the corner spaces between adjacentplane wall portions; additional support for the out of balance loads onthe frame members 5 immediately adjacent the corners may be convenientlyprovided by suitable ties or the like between the outer rigid shell 4and said frame members.

It will be appreciated that the fillings 6, 16 may be of any suitableload-bearing thermal insulation material, and preferably the materialwill have a relatively low co-efficient of expansion as is the case withbalsa wood which varies beween approximately 2 to 8 X l0' unit/unit/F.depending upon the direction of the grain. However, it may be thatmaterials having a significantly higher co-efficient of expansion couldbe used. One such material is polyurethane foam which has a co-efficientof approzimately 50 X unit/unit/F. and the panels to fit within andbetween the boxes 9 would be built up from one or moresprayed layers offoam with prehaps re-inforcement netting between at least some of thelayers to cater for the significant decrease in overall dimensions ofthe panels which would inevitably take place on cooldown of thecontainer to the temperature of the liquefied gas, e.g., --l6l C. forLNG, compressed fibreglass or like fibrous material would be insertedbetween the edges of the panels and the sides 10 of the boxes. Also inorder to reduce the tendency of these panels to bow at the liquefied gastemperature as a result of the large temperature gradicat which would bepresent across the thickness of the panels, said panels may be ofahonecomb construction, for example, as described in our British Pat. No.932,58 1, the spaces'in the honeycomb being filled with the polyurethanefoam. With the present invention it will be appreciated that the fluidimpervious inner and outer sheet described in that specification asbeing bonded to the faces of the panel will not be required since theirfunction is taken by the faces 7, 8 of the boxes 9. However, as a resultof the appreciable contraction that would take place in the panels,these panels may not be so effective as balsa wood panels for acting askeys to maintain the positions of the. faces 7 of the plane-facedportions of the boxes as discussed here inbefore.

I claim:

1. a. An integrated tank container for the bulk storage or transport ofliquids at temperatures greatly differing from ambient temperature,

b. 'said container comprising a housing of loadbearing thermalinsulation supported within an outer rigid shell, said housing beingbuilt up of fluid-tight closed shallow boxes made of flexible sheetmaterial and filled with load-bearing insulation material, said boxesbeing set in spaced edge to-edge alignment to form said housing,

c. said shallow boxes each having two generally parallel opposed mainwall faces of large area, one being a front face and disposed toward theinside of the tank, the other being a back face, said wall faces beingspaced from each other by relatively narrow continuous side wallmembers,

(1. said back faces of the respective boxes having peripheral edgeportions extending out in the plane of the back faces beyond the sidewall members,

e. said extended portions of the back faces being attached to a supportframework carried by the outer rigid shell, and to each other inliquid-tight fashion to provide a secondary membrane,

f. said front faces having peripheral edge portions extending out beyondsaid side wall members, said extended portions of the front faces beingattached to each other in liquid-tight fashion to provide a primarymembrane,

g. the sides of said container being substantially plane-faced, I

h. where those boxes providing the plane-faced portions contain fillingsof said load-bearing thermal insulation,

i. the corner portions of the container being provided by curved boxeswhich contain fillings of thermal insulation material which is of aloose or resilient nature,

j. wherein the walls of the boxes include said peripheral edge portionsproviding the secondary membrane extending beyond said boxes,

k. a set of connecting members attached to the support framework forsealing together adjacent edge portions,

l. a further set of connecting members for scaling together the facesproviding the primary membrane,

m. each space defined between the two sets of connecting members and theadjacent boxes containing a further filling of load-bearing insulationmaterial,

n. wherein each member of the two sets of connecting members is ofgenerally T-shaped cross-section,

o. and .sealing between the faces to provide the primary and secondarymembranes is effected by the arms of the respective members being weldedto said faces.

2. A container according to claim 1,

p. wherein said further fillings are rigid, elongated members formedwith slots which embrace the stems of the set of connecting members forthe secondary membrane to locate said further fillings in position.

- 3,800,970 7 I 1 8 3. a. An integrated tank container for the bulkstorextended portions of the front faces being attached age or transportof liquids at temperatures greatly difto each other in liquid-tightfashion to provide a fering from ambient temperature, primary membrane,

b. said container comprising a housing of loadbearing thermal insulationsupported within an g. wherein the walls of the boxes include saidperipheral edge portions providing the secondary memouter rigid shell,said housing being built up of brane extending beyond Said boxesfluid-tight closed Shallow {30x85 made P flexlble h. a set of connectingmembers attached to the supiheet gt ggl sgz d b l lz s ggi rg ggt gsszzzgglz g z' port framework for sealing together adjacent edge Iportions, ahgnment to saild housmg l] 10 i. a further set of connectingmembers for sealing to- 53:? iziigg g i sgfi zi gz ifg f 2: I ether thefaces Providing the Primary membrane, being a from face and disposedtoward the.mS1de j. each space defined between the two sets of conof thetank, the other being a back face, said wall b d th adace t boxescontaim faces being spaced from each other by relatively P mg mem an 8 Jnarrow continuous side wall members mg a further filling of load-beannginsulation mated. said back faces of the respective boxes havingperipheral edge portions extending out in the plane of k' wherem hmember of the two Sets of connect' the back faces beyond the side wallmembers, mg members 15 Ofgenerany p cross'secnon, e. said extendedportions of the back faces being attached to a support framework carriedby the outer and Sealing between the faces Pmvlde the P rigid shell, andto each other in liquid-tight fashion mary and secondary membranes iseffected by the to provide a secondary membrane, arms of the respectivemembers being welded to f. said front faces having peripheral edgeportions exsaid faces.

tending out beyond said side wall members, said

1. A. An integrated tank container for the bulk storage or transport ofliquids at temperatures greatly differing from ambient temperature, b.said container comprising a housing of load-bearing thermal insulationsupported within an outer rigid shell, said housing being built up offluid-tight closed shallow boxes made of flexible sheet material andfilled with load-bearing insulation material, said boxes being set inspaced edge-to-edge alignment to form said housing, c. said shallowboxes each having two generally parallel opposed main wall faces oflarge area, one being a front face and disposed toward the inside of thetank, the other being a back face, said wall faces being spaced fromeach other by relatively narrow continuous side wall members, d. saidback faces of the respective boxes having peripheral edge portionsextending out in the plane of the back faces beyond the side wallmembers, e. said extended portions of the back faces being attached to asupport framework carried by the outer rigid shell, and to each other inliquid-tiGht fashion to provide a secondary membrane, f. said frontfaces having peripheral edge portions extending out beyond said sidewall members, said extended portions of the front faces being attachedto each other in liquid-tight fashion to provide a primary membrane, g.the sides of said container being substantially plane-faced, h. whereinthose boxes providing the plane-faced portions contain fillings of saidload-bearing thermal insulation, i. the corner portions of the containerbeing provided by curved boxes which contain fillings of thermalinsulation material which is of a loose or resilient nature, j. whereinthe walls of the boxes include said peripheral edge portions providingthe secondary membrane extending beyond said boxes, k. a set ofconnecting members attached to the support framework for sealingtogether adjacent edge portions, l. a further set of connecting membersfor sealing together the faces providing the primary membrane, m. eachspace defined between the two sets of connecting members and theadjacent boxes containing a further filling of loadbearing insulationmaterial, n. wherein each member of the two sets of connecting membersis of generally T-shaped cross-section, o. and sealing between the facesto provide the primary and secondary membranes is effected by the armsof the respective members being welded to said faces.
 2. A containeraccording to claim 1, p. wherein said further fillings are rigid,elongated members formed with slots which embrace the stems of the setof connecting members for the secondary membrane to locate said furtherfillings in position.
 3. a. An integrated tank container for the bulkstorage or transport of liquids at temperatures greatly differing fromambient temperature, b. said container comprising a housing ofload-bearing thermal insulation supported within an outer rigid shell,said housing being built up of fluid-tight closed shallow boxes made offlexible sheet material and filled with load-bearing insulationmaterial, said boxes being set in spaced edge-to-edge alignment to formsaid housing, c. said shallow boxes each having two generally parallelopposed main wall faces of large area, one being a front face anddisposed toward the inside of the tank, the other being a back face,said wall faces being spaced from each other by relatively narrowcontinuous side wall members, d. said back faces of the respective boxeshaving peripheral edge portions extending out in the plane of the backfaces beyond the side wall members, e. said extended portions of theback faces being attached to a support framework carried by the outerrigid shell, and to each other in liquid-tight fashion to provide asecondary membrane, f. said front faces having peripheral edge portionsextending out beyond said side wall members, said extended portions ofthe front faces being attached to each other in liquid-tight fashion toprovide a primary membrane, g. wherein the walls of the boxes includesaid peripheral edge portions providing the secondary membrane extendingbeyond said boxes, h. a set of connecting members attached to thesupport framework for sealing together adjacent edge portions, i. afurther set of connecting members for sealing together the facesproviding the primary membrane, j. each space defined between the twosets of connecting members and the adjacent boxes containing a furtherfilling of load-bearing insulation material, k. wherein each member ofthe two sets of connecting members is of generally T-shapedcross-section, l. and sealing between the faces to provide the primaryand secondary membranes is effected by the arms of the respectivemembers being welded to said faces.